The UK has not yet triggered divorce proceedings following its June vote to leave the EU, but the political fallout on a continent already reeling from the financial crisis, a surge in migration and a spate of terror attacks has been savage.

Even European Commission president Jean-Claude Juncker admitted this week that the bloc was facing "an existential crisis".

In his annual speech to the European Parliament, Mr Juncker tried to rally support by promising to boost security and revive the moribund economy.

However, his suggestion to create a quasi-European army with shared assets and a single military HQ is likely to deepen the divisions between EU countries.

Mr Juncker said being a soft power was not enough in a world that was becoming "ever more dangerous", and the EU should "move towards common military resources that, in certain cases, could be called upon by the union, in full compatibility with Nato".

He also wants to create a single military headquarters for joint EU missions and a "European defence fund" to boost research and development.

While the move will have support in Germany and France - and, to some extent, in Belgium, the Netherlands, Luxembourg, Hungary and other eastern European states - it could cause a rift with Ireland, Austria, Sweden and Finland, the EU's "neutral" states.

The creation of a "common defence" requires a unanimous vote under the EU treaty, but a group of countries can set up "permanent structured cooperation", which requires only a majority vote.

Ireland has a specific opt-out on this, which says the Lisbon treaty "does not provide for the creation of a European army", but there could be problems if a group of "cooperating" states decided to intervene in Syria under an EU banner without consulting their EU partners.

The move would not have been possible before Brexit as the UK has been traditionally against any challenges to the primacy of Nato, but the EU sands are now shifting.

However, Donald Tusk, the man who chairs the regular summits of EU leaders, is keen to avoid sweeping gestures that he fears could backfire.

"Cooperation should be as much as possible concentrated on practical things," said one senior EU official of Mr Juncker's comments.

"Too much of a discussion on grand visions which will not necessarily materialise can, in principle, be counter- productive."

At a meeting of EU leaders in Bratislava tomorrow, Mr Tusk will try to forge some kind of consensus between countries in the east, who are warring with the EU on refugee quotas; those in the south, who want more done to revive jobs and growth; and those in the north, who are struggling to govern against populist, anti-EU political movements.

His strategy is to focus on border control and anti- terrorism or, as he describes it, "bringing back the feeling of security and order" to the EU.

He wants to return decision- making to governments, taking it away from Brussels which, in the words of Slovak premier Robert Fico, has "negative connotations".

Mr Juncker sensed the political tide was turning and did not make any power grabs.

Instead, his speech sought to win European citizens round with promises to double the EU's investment fund to more than €600bn, roll out faster broadband across the continent, extend jobs training and funding for the under-25s and create a European volunteer corps.

Crucial

He said it was a "crucial time to deliver a better Europe, a Europe that protects and preserves the European way of life".

It was a speech that also sought to appease EU governments. For example, Mr Juncker rowed back on singling out Ireland for censure over the Apple case. While his prepared remarks mentioned Apple's "illegal backroom deals" here, his speech made only a vague reference to fair taxation.

The speech made no mention of divisive issues such as the EU-US trade deal, relations with Turkey or further eurozone integration.

However, he complained that there was still not "enough union" in Europe, a theme likely to resurface as the bloc prepares to celebrate its 60th anniversary next March.

Mr Tusk's letter to the Taois- each and other EU leaders ahead of the Bratislava summit also spoke of the need to forge a "sense of our community" before the historic anniversary.

However, he has worked hard to dampen expectations ahead of the meeting tomorrow , the EU's second without Britain, but certainly not its last.